/**
 * 
 */
   function mouse(evt) {
    var e = evt || window.event
    var target = e.target || e.srcElement
    if (target.nodeName == 'LI') {
        var boxObj = document.querySelector('.box')

        var w = boxObj.clientWidth
        var h = boxObj.clientHeight
        boxObj.style.display = 'block'
        //定位，然后把left、top改成鼠标位置
        boxObj.style.left = e.clientX - w / 2 + 'px'
        boxObj.style.top = e.clientY - h / 2 - 25 + 'px'
    }
    //移除隐藏
    ulObj.onmouseout = function () {
        var boxObj = document.querySelector('.box')
        boxObj.style.display = 'none'
    }
}

